Talks on extending Philadelphia Phillies pitcher Steve Carlton's contract were at an impasse yesterday because of an arbitrator's award of a $1 million contract to Los Angeles Dodgers pitcher Fernando Valenzuela.

Phillies President Bill Giles said they and agent Dave Landfield agreed in late January to extend Carlton's contract through the 1986 season, but that Landfield demanded more money at a meeting Monday.

The agreement, Giles said, called for paying Carlton $700,000 in 1983 and $1,150,000 in the 1984, 1985 and 1986 seasons, with all the money guaranteed. After that, the contract would be renewable on a year-to-year basis at the Phillies' option.

Giles said he and Landfield shook hands and that only the exact wording of the contract needed to be completed. The current contract for Carlton, 38, baseball's only four-time winner of the Cy Young award, runs through the end of the 1984 season.

However, when the completed contract was presented Monday, Giles said, Landfield indicated concern that last week's award to Valenzuela might mean Valenzuela soon would earn more than Carlton.

Giles said the Phillies will not renegotiate financial terms; if the pact is not acceptable, they will wait until the present contract expires before resuming negotiations.